@LeeC2202 In similar function. But I also tried, using fade in and fade out native without the bool condition.
e.g. GTA.Native.Function.Call(Hash.DO_SCREEN_FADE_OUT, 3000);
Wait(XSeconds);
GTA.Native.Function.Call(Hash.DO_SCREEN_FADE_IN, 3000);

@ashishcw It will work fine without, I use it in my Auto-Snap mod with just a line like this Function.Call(Hash.DO_SCREEN_FADE_IN, FadeTimer); but you have to check if it has faded out every frame.

Just one other slight digression... you only waited 4 hours before bumping and tagging people. Remember the timezone differences and give people more time to respond... I have waited days before getting answers sometimes. Metaphorically banging on people's doors might not always get the response you desire.

@ashishcw I've always tended to use this kind of system, so it's pure habit now to stick with it

enum PlaybackState { FadeIn, FadeOut, NormalUpdating, BlackScreenProcessing };
// Inside Class declarations
PlaybackState PlayState;
int FadeTimer = 1000;
// In OnTick or whatever Update function system you use
switch (PlayState)
{
// FadeIn state, waits until the screen is fully faded in and then changes state
case PlaybackState.FadeIn:
if (Function.Call<bool>(Hash.IS_SCREEN_FADED_IN))
{
PlayState = PlaybackState.NormalUpdating;
}
break;
// This state is for when the screen is fully faded in
case PlaybackState.NormalUpdating:
// Do normal update processing here
// Call this when you want to fade the screen out
// Function.Call(Hash.DO_SCREEN_FADE_OUT, FadeTimer);
break;
case PlaybackState.FadeOut:
if (Function.Call<bool>(Hash.IS_SCREEN_FADED_OUT))
{
PlayState = PlaybackState.BlackScreenProcessing;
}
break;
// This state is for when the screen is fully faded out
case PlaybackState.BlackScreenProcessing:
// Do any processing here when the screen is blacked out
// Call this when you want to fade the screen in
// Function.Call(Hash.DO_SCREEN_FADE_IN, FadeTimer);
PlayState = PlaybackState.FadeIn;
break;
}

So for all not known how to use fade in / fade out effect, solution is, to add the later part in tick function, so where game will be constantly checking if the screen has faded out. Apart from it I didn't find any other solution working(I could be wrong here).